1. Field of the Invention
The present invention relates to an electrical contact to be electrically connected with a first electrical part such as a semiconductor device (herein after called “IC package”), etc. and to a socket for electrical parts in which the electrical contact is disposed.
2. Prior Art of the Invention
In a known art, there has been provided an electrical contact of this kind, for example, as shown in FIG. 14 (Patent Document 1: Japanese unexamined Patent Publication No. JP H10-239349 A1). This electrical contact 1 comprises a plunger 2 and a spring member 3 and is held by both an upper-side holding member 5 and a lower-side holding member 6 of the socket body 4. The electrical contact 1 is structured to make an electrical connection between a wiring board 7 and an electrical part (“IC package”, not shown) which is accommodated on an upper side of the electrical contact.
More precisely, the plunger 2 has a contact portion 2a to be contacted with the electrical part at an upper end portion thereof, a flange portion 2b at a middle portion thereof for retaining the plunger, and a shaft portion 2c formed on a lower side of the flange portion 2b. 
Further, the spring member 3 comprises a normally-wound portion 3a in which a wire member is retractably wound and a closely-wound portion 3b in which the wiring member is closely wound. Both wound portions are disposed continuously in the vertical direction. The shaft portion 2c of the plunger 2 is inserted into the normally-wound portion 3a. Electrical connection can be established by making contact between the spring member 3 and the plunger 2, and the closely-wound portion 3b of the spring member 3 is structured to be electrically connected with an electrode portion 7a of the wiring board 7.
In such type of contact pin, when the electrical part (“IC package”) is accommodated on the upper side of the plunger 2 and then the plunger 2 is pushed down by the electrical part, the normally-wound portion 3a of the spring member 3 is compressed and thus the plunger 2 is moved downward. When this compression force acts on the contact portion 2a of the plunger 2 and the closely-wound portion 3b of the spring member 3, the contact portion 2a contacts a terminal of the electrical part and the closely-wound portion 3b contacts the electrode portion 7a of the wiring board 7 with a predetermined pressure respectively.
At this stage, the terminal of the electrical part and the electrode portion 7a of the wiring board 7 can be electrically connected, and then burn-in test, etc. of the electrical part (“IC package”) are carried out.
In such known contact pin, however, the plunger 2 is formed from a rod-like pin through cutting work, so that the shape forming of such plunger is time-consuming and cost-increasing. In addition, the resulting plunger itself is heavy, being inconvenient. In particular, the cutting work for producing a crown-like shape contact portion 2a which is to be contacted with the IC package, is time-consuming.